The security and safety around underground infrastructures, such as oil and gas transportation pipelines, has become an important endeavor. Many studies show that most damage to pipelines is third-party damage, which refers to damage caused by earth working (e.g., using a digger or excavator) in the vicinity of an existing pipeline, which is insufficiently spotted or insufficiently protected. The Pipeline Research Council International (PRCI) studies on gas pipelines indicated that 40% of pipeline damage incidents are caused by third-party damage.
A high percentage of failures can be attributed to encroachment and this increasing trend is expected to increase as remote areas become urbanized. This is due to the fact that increases in the population and urbanization lead to an increase in development activities including construction and thus increasing the likelihood of third-party damages. Pipeline failure frequencies in developed areas are four (4) times that in rural areas.
Today, concrete is used for the protection of buried pipelines. Pre-fabricated or casted on-site, concretes slabs are attractive because of their robustness and availability of the material. However, concrete slabs are heavy which implies constraints on the necessary devices (cranes, trucks) and on employees operating the protection, as slab handling is risky and requires a minimal number of operators. Another drawback is the difficulty in handling concrete slabs during construction as well as maintenance operation.
Polymer slabs provide a number of advantages compared to concrete slabs. In particular, the weight of polymer slabs is significantly less for an equivalent surface of protection. This lightweight advantage leads to saving cost. Polymer slabs offer increased functionality as well. Installation of polymer slabs and concrete slabs, however, requires digging of a trench, wherein the width of the trench is driven by the pipeline diameter. Typically, the width of the trench will range between one to two meters. After digging the trench, the slabs are installed followed by backfilling the trench.
One alternative to polymer slabs is installation of polymer meshes that resemble woven netting. Although the mesh solution is less resistant than the HDPE slab, a mesh can withstand, for example, a force equal to 210,000N, which is in general sufficiently robust to protect subsurface structures. Protecting subsurface infrastructure with a mesh, however, requires burying a larger mesh than a slab. This is due to the flexibility of the mesh which is compensated through leveraging a larger friction surface between the protection layer and the soil. Hence, the installation of a mesh requires digging of a wider trench than for polymer slabs.